The present invention relates to a device for monitoring the cell voltage of cells of a rechargeable battery which has a number of cells which are electrically connected to one another, each having a monitoring unit per cell for detection of the cell voltage of the associated cell and having at least one current interruption switch for interruption of the current flowing through at least one associated cell.
Individual cells in a rechargeable battery which has a plurality of cells that are connected to one another have to be monitored in order, for example in the case of lithium-ion rechargeable batteries, to prevent irreversible damage to the cells as a result of overcharging or deep-discharging.
DE 198 01 746 A1 describes a circuit for monitoring a multiple-cell rechargeable battery, in which the complexity for the electrical connection between monitoring electronics and the cells as well as a central control unit used by plugging a board for the monitoring electronics onto the pole connections of the cells to be monitored is reduced. The monitoring electronics measure the cell voltage of an associated cell as well as the pole connection temperatures, and pass these measurements to a central battery management device, via a data bus.
DE 199 21 675 A1 discloses a method for detection of characteristic variables and measurement variables of battery sets, in which measurement variables for a cell, such as the cell voltage, the cell temperature and the cell pressures, are compared with the output variables of a measurement module for an adjacent cell. The result from the variable comparison is passed on as an output signal to the next measurement module, and is available in the last measurement module in the chain of cells in a rechargeable battery as the output signal from the entire measurement chain.
DE 28 27 479 A1 describes a circuit arrangement for the cell voltages of individual cells in a rechargeable battery, in which the voltages of the cells are monitored directly by optocouplers connected in series. If a threshold voltage, which may be scattered to a major extent, is undershot, a switch is opened in order to interrupt the current flowing through the rechargeable battery.
Against this background, it would be desirable to provide an improved device for monitoring the cell voltage of cells in a rechargeable battery.